Federal investigators targeted physicist Wen Ho Lee as an espionage suspect largely because he is a Chinese American and they still do not have a "shred of evidence" that he leaked nuclear secrets to China, the former chief of counterintelligence at Los Alamos National Laboratory said yesterday.

Breaking a long public silence, Robert S. Vrooman also said he does not believe that China obtained top-secret information about U.S. nuclear warheads from Los Alamos or any other laboratory belonging to the Department of Energy. The stolen data, he said, could have come from documents distributed to "hundreds of locations throughout the U.S. government" as well as to private defense contractors.

While some Chinese American rights organizations previously have charged that Lee was unfairly targeted, Vrooman is the first high-ranking participant in the investigation to state that Lee's ethnicity was "a major factor" in his identification as the government's prime suspect.

Vrooman made his remarks in an interview with The Washington Post less than a week after Energy Secretary Bill Richardson recommended disciplinary action against him and two other former Los Alamos officials for alleged missteps during the espionage probe.

"I've had a distinguished career," said Vrooman, 62, a former CIA operations officer who retired from Los Alamos in March 1998 and is now working there as a consultant. "And I'm not going to go down in history as the guy who screwed up this case, because I wasn't. This case was screwed up because there was nothing there -- it was built on thin air."

In a separate statement faxed to The Post, Vrooman said Lee "was identified by the Department of Energy's Office of Counterintelligence as the prime suspect based on an, at best, cursory investigation at only two facilities, Los Alamos and Lawrence Livermore National Laboratory."

While "details of this investigation are still classified," he added, "it can be said at this time that Mr. Lee's ethnicity was a major factor."

The fact that Lee had visited China and met with officials at a physics institute there in 1986 and 1988 became another strike against him, Vrooman said, even though "Caucasians at Los Alamos who went to the same institute and visited the same people -- I counted 13 of them -- were left out of the investigation."

A bipartisan congressional committee chaired by Rep. Christopher Cox (R-Calif.) concluded in May that China had stolen information about the design of U.S. nuclear weapons, including the nation's most advanced warhead, the miniaturized W-88.

Vrooman said, however, that the information could have leaked from many sources. While "no complete inventory of documents containing this data has been made or is possible," he said, one "rather detailed description of the W-88" was distributed to 548 different addresses at the Defense Department, Energy Department, various defense firms, the armed services and even the National Guard.

Lee, a Taiwan-born nuclear physicist and U.S. citizen, was fired in March for alleged violations of Los Alamos's security regulations. He has denied ever passing secrets to China, and he has not been charged with any crime. The Justice Department is weighing whether to charge him with transferring classified information from the secure computer system at Los Alamos to his vulnerable desktop computer.

In recommending last week that Los Alamos take some unspecified disciplinary action against Vrooman, Richardson said Vrooman had failed to remove Lee from the laboratory's top-secret Division X or to deny him access to secret information after he came under suspicion of espionage.

Vrooman countered yesterday that the decision to allow Lee to keep working was made in 1997 by the Energy Department's chief intelligence officer, Notra Trulock -- the same officer who had identified Lee as the government's main suspect.

"We could not have removed [Lee] from access [to classified materials] without alerting him, and that would have just blown everything," Vrooman said. "It was a judgment call -- I think it was the right call. And it was made in concert with the FBI."

Richardson also recommended unspecified disciplinary action against Terry Craig, another counterintelligence official at Los Alamos, saying Craig had failed to inform the FBI in 1996 that Lee had signed a waiver authorizing officials to search his computer.

Craig told The Washington Post yesterday that no one in the FBI ever asked him to look into whether Lee had signed a waiver. He said he lacked authority to perform the research without authorization from FBI investigators.

"By leaking our names, [DOE officials] in essence damaged our reputations -- and it seems to me there's way too much of that going on," said Craig, 55, a career employee at Los Alamos who transferred two months ago to another job unrelated to counterintelligence.

The third official facing disciplinary action, former Los Alamos director Sig Hecker, who remains a scientist at the facility, has not returned telephone messages.

An Energy Department spokeswoman said Richardson recommended disciplinary measures only after commissioning two internal inquiries. "Based on the evidence gathered in these inquiries, the secretary concluded that these individuals had specific responsibilities with respect to the FBI investigation that they did not meet," the spokeswoman said.

Richardson also has denied that Lee's ethnicity played a major role in the investigation, and he has assured employees at the national laboratories that he will not tolerate any discrimination against Chinese Americans.

Both Craig and Vrooman said there is no evidence pinpointing Los Alamos as the source of secrets stolen by China. Similar conclusions were reached earlier this year by the CIA, the President's Foreign Intelligence Advisory Board and the Senate Governmental Affairs Committee.

Vrooman also said he disagreed when Trulock, the Energy Department intelligence official, concluded in 1995 that China had stolen the design of the W-88. Trulock's conclusion was based largely on a document obtained by the CIA from a Chinese intelligence agent showing the warhead's explosive yield and external dimensions.

"If I give you the exterior dimensions of my home, could you recreate the floor plan? No," Vrooman said.

Despite those doubts, Vrooman said, he pressed the FBI to pursue the case vigorously and succeeded in getting the bureau to replace an agent who was busy with other matters. But he said he now believes "they picked the wrong guy for the wrong reason."

"I have been an outspoken critic of the flawed investigation that identified Mr. Lee as the prime suspect in this case," Vrooman said. "I do not agree with Mr. Trulock or with the secretary of energy that the information obtained by the Chinese came from the Department of Energy. I consider disciplinary action against me to be retaliation for opposing them on this issue."